A solution is prepared at 75 °C by dissolving 50.0 g of A in 100 g of water.When this solution is cooled to 15 °C what happens based on the following solubility plot for A.
A) Solid A crystallizes and the solution is unsaturated.
B) Solid A dissolves and the solution is supersaturated.
C) Solid A crystallizes and the solution is saturated.
D) Solid A dissolves and the solution is unsaturated.

Question

A solution is prepared at 75 °C by dissolving 50.0 g of A in 100 g of water.When this solution is cooled to 15 °C what happens based on the following solubility plot for A. 
A) Solid A crystallizes and the solution is unsaturated. 
B) Solid A dissolves and the solution is supersaturated. 
C) Solid A crystallizes and the solution is saturated. 
D) Solid A dissolves and the solution is unsaturated.

Quizplus · Accepted Answer

Looking at the solubility plot, we can see that at 75 °C, the solubility of A is greater than 50 g/100 g of water. Therefore, the solution is saturated. When the solution is cooled to 15 °C, the solubility of A decreases and becomes less than 50 g/100 g of water. This means that the solution is now supersaturated and solid A will begin to crystallize out of the solution until it becomes saturated again. Therefore, choice C is the best answer.

A Solution Is Prepared at 75 °C by Dissolving 50